Paul Atreides, the son of DukeLeto Atreides I, used the Litany when the Reverend MotherGaius Helen Mohiam compelled him to put his right hand in a device that causes pain as a test of his presence of mind. The litany helped him to withstand the excruciating agony.
It was a test of his humanity in a qualitative sense. A person whose nature is still primarily bestial recoils from pain and seeks to flee it to preserve itself, a person of higher nature goes through it and out the other side in order to remove the threat permanently.

"You've heard of animals chewing off a leg to escape a trap? There's an animal kind of trick. A human would remain in the trap, endure the pain, feigning death that he might kill the trapper and remove a threat to his kind."

The litany has also appeared in other non-Dune related media. For instance, it was frequently recited by Pete, a supporting character in Earthworm Jim, the animated series based on the video game of the same name.